The present invention generally relates to a system and method for interpreting sonic data. In particular, the present invention relates to a system and method for detecting flaws and/or defects in parts through analysis of ultrasonic data. The present invention relates generally to the nondestructive evaluation of materials, and more particularly to laser ultrasound inspection of engineering materials with ultrasonic bulk, surface, and Lamb waves.
Measurement of ultrasound is commonly performed to characterize materials. This includes measuring and detecting structures, and can be implemented to find defects or flaws within the parts or contained in the materials making up the parts.
Within many industries, inspection of engineering materials has extreme importance in assuring continued performance of structures. In other systems, parts or components need to be evaluated for defects or flaws. Many times these parts may be highly sensitive pieces made in complex engineered fashion and made up of complex materials.
Generated sonic waves propagate through an article. Defects in the part may reflect the waves or change other physical parameters associated with the wave. These sonic waves may be detected, and stored for later analysis.
These waveforms may be converted into a visual image to aid in diagnosing problems. Many times, in a typical system, and arrival of the sonic energy may be used to determine visually where a defect is, and possibly what type of defect is present.
However, this typical analysis of the collected waves usually only indicates a presence of a problem, and may not completely diagnose or locate a particular defect in the part or underlying material. Thus, while the conventional analysis may indicate the presence of a defect or flaw, it may not adequately describe the type and/or physical location of the defect or flaw.
This problem is exacerbated when dealing with composite parts. The interlocking or coupled relationship of various layers of materials, or type of construction gives rise to multiple complex echoes. Thus, in these systems, the echo waveform may not be easily used for visualization or interpretation.
As such, many typical sonic detection systems suffer from deficiencies in providing accurate indications of defects. Many other problems and disadvantages of the prior art will become apparent to one skilled in the art after comparing such prior art with the present invention as described herein.
Various aspects of the invention may be found in a method for detecting more and more defects in manufactured object. The invention converts complex measured ultrasonic waveforms into basis functions indicative of any defects within that part. First, a series of reference waveforms corresponding to the ideal part and or to flaws of various types at various places in depths within the part are generated. These reference waveforms form a series of basis functions that may be helpful in describing any observed waveform. Since a measured waveform may be represented in terms of an inner sum of these basis functions and the amplitudes of each basis function that correspond to a presence of that particular type of defect, the presence of the basis function corresponding to a particular type of defect indicates that in the particular type of defect is present.
In typical measurement systems, a series of waveforms may be generated from the part. Even in a simple layered structure, a complex series of echoes is generated in an ideal part. Additionally, the presence of any defects will alter the waveform within the part. However, due to the complex nature of the sonic characteristics of the part, defect location by echo timing is problematic.
However, in the present system, the waveforms for particular defects at particular location(s) may be stored as waveforms, and these may be added in combination with the ideal waveform to produce a reference waveform. The combination of a reference ideal waveform for the part, and the basis functions for defects are compared against the received waveform for the part. The presence of any of the basis functions for a corresponding defect thus indicates the location and type of defect present in the part.
In this way, a defect in an interface is represented by the amplitude corresponding to that sort of defect, rather than as a series of complex echoes. This technique may be applied in a variety of situations. This includes simple parts where multiple echoes are generated from a single flaw, for example, a reverberation against either a front or back wall, or for separation and identification of flaws near the front or rear surfaces of the part.
The various comparison waveforms or representations of such waveforms may be generated in several ways. For example, the basis functions may be derived through a computational model, or they may be derived through experimental measurements of reference parts. In the case of basis functions referring to defects, the reference parts were contained a known defect. Thus the type and parameters of the waveforms generated by the specific defect may be groomed from such experimental measurement.
Other aspects of the invention include describing the defective structures by using the amplitudes of these basis functions to draw images. When the presence of the basis function indicating a specific flaw or defect type is determined, an image of the part or location may be generated. A simple graph such as a graph of amplitude versus location may indicate the specific point where a flaw is located. Other imaging schemes may include B-scans and C-scans where both B and C are capitalized. In these B-scans or C-scans, the parameter viewed would be the amplitude of various basis functions. Thus, the presence of an amplitude for a basis function at a particular location in a B-scan or C-scan would indicate the presence of the particular type of defect associated with the basis function at the point on the object.
In another aspect of the invention, the detection of flaws or defects is improved even in the presence of noise. Further descriptions of how this method aids in the detection of such defects or flaws in the presence of noise is described in detail later in this application.
Other aspects, advantages and novel features of the present invention will become apparent from the detailed description of the invention when considered in conjunction with the accompanying drawings.